1. Field of the Invention
The invention relates generally to process for converting carbon dioxide in an exothermic reaction, and more particularly, to such process whereby energy released in the exothermic reaction is used in a preceding carbon dioxide enrichment step.
2. Description of the Related Art
Prior art processes for converting carbon dioxide to liquid products, such as methanol, are known. Such processes require feed gases having high carbon dioxide content. For this reason such processes generally are integrated with industrial plants that produce gases having high carbon dioxide content, such as power plants, refineries, and the like. Such gases typically contain contaminants, such as SOx, that are corrosive and act as poisons to carbon dioxide conversion catalysts. The feed gases therefore need to be purified before they can be used in the carbon dioxide conversion process.
Carbon dioxide conversion processes, such as the conversion to methanol, are strongly exothermic. Thermal energy must continuously be withdrawn from the carbon dioxide conversion reactor. To avoid energy waste and thermal pollution of the environment, carbon dioxide conversion plants need to be operated in conjunction with other industrial processes having a net energy demand, so that heat generated by the carbon dioxide conversion process can be put to good economic use.
Thus, there is a need for a carbon dioxide conversion process that is sufficiently energy balanced to be operated in stand-alone fashion. There is a further need for a carbon dioxide conversion process that can use feedstock gases that have relatively low carbon dioxide concentration, such as ambient air.